Rankine cycle device of internal combustion engine

ABSTRACT

In a Rankine cycle system for an internal combustion engine, including an evaporator ( 3 ) for generating a vapor, an expander ( 4 ) for converting a heat energy of the vapor into a mechanical energy, a condenser ( 5 ) for cooling the vapor discharged from the expander ( 4 ) to restore it into water, a tank ( 6 ) for storage of the water from the condenser ( 5 ), and supply pumps ( 7, 8 ) for supplying the water in said tank ( 6 ) to the evaporator ( 3 ) in a pressurizing manner, the water in the tank ( 6 ) is supplied via a water jacket ( 105 ) of the internal combustion engine ( 1 ) to a dispensing valve ( 106 ) by the lower-pressure pump ( 7 ). A portion of the water dispensed by the dispensing valve ( 106 ) is further pressurized and supplied to the evaporator ( 3 ) by the higher-pressure pump ( 8 ), and another portion of the water dispensed by the dispensing valve ( 106 ) is discharged to the tank ( 6 ) after dissipating its heat in an auxiliary ( 110 ) such as a heater for heating a vehicle compartment and the like. Thus, it is possible to sufficiently cool heated portions of the internal combustion engine ( 1 ) by the water which is a liquid-phase working medium, while maintaining the performance of the Rankine cycle system, thereby aiming at the disuse of a radiator.

FIELD OF THE INVENTION

[0001] The present invention relates to a Rankine cycle system utilizinga waste heat from an internal combustion engine, and particularly, to aRankine cycle system designed so that heated portions of an internalcombustion engine can be cooled by a working medium.

BACKGROUND ART

[0002] A Rankine cycle system is described in Japanese Utility ModelApplication Laid-open No.59-174308, which includes an evaporator forheating a liquid-phase working medium by an exhaust gas from an internalcombustion engine to generate a gas-phase working medium, an expanderdriven by the gas-phase working medium generated in the evaporator, acondenser for cooling the gas-phase working medium passed through theexpander to restore it into the liquid-phase working medium, and asupply pump for supplying the liquid-phase working medium from thecondenser in a pressurizing manner to the evaporator.

[0003] In the above-described conventional Rankine cycle system, thewater as the liquid-phase working medium is passed not only through theinside of the evaporator mounted in an exhaust pipe from the internalcombustion engine, but also through the inside of a cooling passagedefined in a cylinder head and a cylinder block to heat them, whereby awaste heat from the internal combustion engine is utilized furthereffectively, and the cylinder head and the cylinder block are cooled bythe liquid-phase working medium, thereby aiming at the disuse of aconventional radiator.

[0004] In general, however, the ratio of the flow rate of the water asthe liquid-phase working medium in the Rankine cycle system to the flowrate of the cooling water for the internal combustion engine is on theorder of 1:100, and thus, the flow rate of the cooling water for theinternal combustion engine is far large, as compared with the flow rateof the water in the Rankine cycle system. The pressure of the watersupplied to the evaporator in the Rankine cycle system is about 100times the pressure of the cooling water supplied to the water jacket ofthe internal combustion engine, resulting in a large difference existingbetween both of the pressures.

[0005] Therefore, it is virtually difficult, because of a largedifference in flow rate and pressure between the water-circulatingpaths, to connect a water-circulating path in the Rankine cycle systemand a water-circulating path for the internal combustion engine in lineto each other to aim at the disuse of a radiator, and there is apossibility that the internal combustion engine might be overheated andthat the Rankine cycle system could not exhibit a sufficientperformance.

DISCLOSURE OF THE INVENTION

[0006] The present invention has been accomplished with the abovecircumstances in view, and it is an object of the present invention toensure that the heated portions of the internal combustion engine can becooled sufficiently by the liquid-phase working medium, whilemaintaining the performance of the Rankine cycle system, thereby aimingat the disuse of a radiator.

[0007] To achieve the above object, according to a first aspect andfeature of the present invention, there is proposed a Rankine cyclesystem for an internal combustion engine, including an evaporator forheating a liquid-phase working medium by a waste heat from an internalcombustion engine to generate a gas-phase working medium, an expanderfor converting a heat energy of the gas-phase working medium dischargedfrom the evaporator into a mechanical energy, a condenser for coolingthe gas-phase working medium discharged from the expander to restore thegas-phase working medium into the liquid-phase working medium, a tankfor storage of the liquid-phase working medium discharged from thecondenser, and pumps for supplying the liquid-phase working medium inthe tank to the evaporator, characterized in that the pumps are alower-pressure pump and a higher-pressure pump, the lower-pressure pumphaving the liquid-phase working medium in the tank pass through acooling means for the internal combustion engine, thereby heating andsupplying the liquid-phase working medium to a dispensing valve, aportion of the liquid-phase working medium dispensed by the dispensingvalve being pressurized by the higher-pressure pump and supplied to theevaporator, another portion of the liquid-phase working medium dispensedby the dispensing valve being discharged to the tank after dissipatingits heat in an auxiliary.

[0008] With the above arrangement, the liquid-phase working medium inthe tank is supplied to the cooling means for the internal combustionengine by the lower pressure pump to cool heated portions of theinternal combustion engine, and thereafter, a portion of theliquid-phase working medium exiting from the cooling means is suppliedfrom the dispensing valve to the higher-pressure pump and supplied in apressurized state to the evaporator in the Rankine cycle system, whileanother portion of the liquid-phase working medium exiting from thecooling means is supplied from the dispensing valve to the auxiliary,and the liquid-phase working medium exiting from the expander in theRankine cycle system and liquefied through the condenser and theliquid-phase working medium dissipating its heat in the auxiliary arereturned to the tank. Therefore, it is possible to supply theliquid-phase working mediums having flow rates and pressures suitablerespectively for the Rankine cycle system and the cooling means, whileuniting a liquid-phase working medium-circulating line in the Rankinecycle system and a liquid-phase working medium-circulating line in thecooling means for the internal combustion engine. Thus, it is possibleto cool the heated portions of the internal combustion enginesufficiently, while maintaining the performance of the Rankine cyclesystem, thereby aiming at the disused of a radiator.

[0009] According to a second aspect and feature of the presentinvention, in addition to the first feature, the liquid-phase workingmedium exiting from the lower-pressure pump is preheated in a heatexchanger mounted in an exhaust pipe in the internal combustion engineand supplied to the cooling means.

[0010] With the above arrangement, the liquid-phase working mediumsupplied from the lower-pressure pump to the cooling means is preheatedin the exchanger mounted in the exhaust pipe and hence, it is possiblenot only to utilize a waste heat of an exhaust gas further effectively,but also to prevent the occurrence of the overcooling by theliquid-phase working medium passed through the cooling means when theinternal combustion engine is at a lower temperature, thereby promotingthe warming of the internal combustion engine.

[0011] According to a third aspect and feature of the present invention,in addition to the first or second feature, a portion of the heatedliquid-phase working medium dispensed from the dispensing valve is usedas a lubricating medium for the expander.

[0012] With the above arrangement, a portion of the heated liquid-phaseworking medium dispensed from the dispensing valve is used as alubricating medium for the expander and hence, it is possible to preventthe dropping of the temperature of the expander due to the lubricatingmedium having a lower temperature to suppress the reduction of theexpanding work, thereby enhancing the efficiency of recovery of thewaste heat from the internal combustion engine.

[0013] According to a fourth aspect and feature of the presentinvention, in addition to the third feature, the portion of theliquid-phase working medium supplied as the lubricating medium issupplied in the form of a gas-phase working medium to an expansionstroke of the expander.

[0014] With the above arrangement, the portion of the liquid-phaseworking medium supplied as the lubricating medium is supplied in theform of the gas-phase working medium to the expansion stroke of theexpander and hence, the heat energy own by the liquid-phase workingmedium serving as the lubricating medium can be utilized effectively toincrease the output from the expander.

[0015] According to a fifth aspect and feature of the present invention,in addition to the second feature, a portion of the heated liquid-phaseworking medium dispensed from the dispensing valve is passed through areducing valve to be converted into a gas-phase working medium, which issupplied to an expansion stroke of the expander.

[0016] With the above arrangement, the portion of the heatedliquid-phase working medium dispensed from the dispensing valve isconverted into the gas-phase working medium by the reducing valve, whichis supplied to the expansion stroke of the expander, and hence, a heatenergy received from the heated portions of the internal combustionengine by the liquid-phase working medium can be utilized effectively toincrease the output from the expander.

[0017] According to a sixth aspect and feature of the present invention,in addition to any of the first to fifth features, water is used as theliquid-phase working medium.

[0018] With the above arrangement, the water, having a wide range oftemperature in which it can be used without variation in compositionsuch as carbonization and the like, is used as the liquid-phase workingmedium. Therefore, the gas-phase working medium in a higher-temperaturestate supplied to the expander and the liquid-phase working medium in alower-temperature state discharged from the cooling medium for theinternal combustion engine can be merged into each other withouthindrance and moreover, when water is used as the lubricating medium,the working medium and the lubricating medium can be mixed with eachother without hindrance.

[0019] Water in an embodiment corresponds to the liquid-phase workingmedium of the present invention; a vapor in the embodiment correspondsto the gas-phase working medium of the present invention; and a waterjacket 105 in the embodiment corresponds to the cooling means of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGS. 1 to 14 show an embodiment of the present invention.

[0021]FIG. 1 is a schematic illustration of a Rankine cycle system foran internal combustion engine;

[0022]FIG. 2 is a vertical sectional view of an expander, correspondingto a sectional view taken along a line 2-2 in FIG. 4;

[0023]FIG. 3 is an enlarged sectional view of an area around arotational axis in FIG. 2;

[0024]FIG. 4 is a sectional view taken along a line 4-4 in FIG. 2;

[0025]FIG. 5 is a sectional view taken along a line 5-5 in FIG. 2;

[0026]FIG. 6 is an enlarged view of a portion of FIG. 4;

[0027]FIG. 7 is an enlarged sectional view taken along a line 7-7 inFIG. 3;

[0028]FIG. 8 is a diagram showing sectional shapes of a rotor chamberand a rotor;

[0029]FIG. 9 is an exploded perspective view of the rotor;

[0030]FIG. 10 is an exploded perspective view of a rotor segment;

[0031]FIG. 11 is an exploded perspective view of a vane;

[0032]FIG. 12 is an exploded perspective view of a rotary valve;

[0033]FIG. 13 is a graph showing the relationship between amounts ofincrement in output from the expander at temperatures of lubricatingwater with respect to the phase in which the lubricating water issupplied to an expansion stroke of the expander; and

[0034]FIG. 14 is a graph showing the relationship between amounts ofincrement in output from the expander in amounts of lubricating watersupplied with respect to the phase in which the lubricating water issupplied to an expansion stroke of the expander.

BEST MODE FOR CARRYING OUT THE INVENTION

[0035] As shown in FIG. 1, a Rankine cycle system 2 for recovering aheat energy of an exhaust gas from an internal combustion engine 1 tooutput a mechanical energy includes an evaporator 3 for generating ahigh-temperature and high-pressure vapor by heating water using theexhaust gas from the internal combustion engine 1 as a heat source, anexpander 4 for outputing a shaft torque by the expansion of thehigh-temperature and high-pressure vapor, a condenser 5 for cooling adropped-temperature and dropped-pressure vapor discharged from theexpander 4 to liquefy it, a tank 6 for storage of the water dischargedfrom the condenser 5, and a lower-pressure pump 7 and a higher-pressurepump 8 for supplying the water in the tank 6 again to the evaporator 3.

[0036] The water in the tank 6 is pressurized to 2 to 3 MPa by thelower-pressure pump 7 disposed on a passage P1 and passed through a heatexchanger 102 mounted in an exhaust pipe 101 for the internal combustionengine 1, where it is preheated. The preheated water passed through theheat exchanger 102 is supplied via a passage P2 to a water jacket 105defined in a cylinder block 103 and a cylinder head 104, and coolsheated portions of the internal combustion engine 1 during passingthereof through the jacket 105. In this case, the water itself robs heatof the heated portion, whereby the temperature thereof is furtherraised. The water exiting from the water jacket 105 is supplied via apassage P3 to a dispensing valve 106, where the water is dispensed intoa first system leading to a passage P4, a second system leading to apassage P5, a third system leading to a passage P6 and a fourth systemleading to passages P7.

[0037] The water dispensed to the first system leading to the passage P4by the dispensing valve 106 is pressurized to a higher pressure equal toor higher than 10 MPa by th higher-pressure pump 8 and supplied to theevaporator 3, where it is subjected to a heat exchange with an exhaustgas having a higher temperature, whereby it is converted into ahigh-temperature and high-pressure vapor, and supplied tohigher-pressure portions of the expander 4 (cylinders 33 of the expander4, which will be described hereinafter). On the other hand, the waterdispensed to the second system leading to the passage P5 by thedispensing valve 106 is passed through a reducing valve 107 incorporatedin the passage P5, whereby it is converted into a vapor having a lowertemperature and a lower pressure as compared with the higher temperatureand higher-pressure vapor, and supplied to lower-pressure portions ofthe expander 4 (vane chambers 50 in the expander 4). In this way, theheated water from the dispensing valve 106 is converted into the vaporby the reducing valve 107 and supplied to the lower-pressure portions ofthe expander 4 and hence, the output from the expander 4 can beincreased by effectively utilizing the heat energy received by the waterfrom water jacket 105 of the internal combustion engine 1. The waterdispensed to the third system leading to the passage P6 is supplied toportions of the expander 4 which are to be lubricated. At this time, theportions to be lubricated of the expander 4 are lubricated using thehigh-temperature water heated in the water jacket 105 and hence, thedropped-temperature and dropped-pressure vapor discharged from theexpander 4 and containing water is supplied to the condenser 5incorporated in the passage P8, where it is subjected to a heat exchangewith cooling air from a cooling fan 109 driven by an electric motor 108,and the resulting condensed water is discharged into the tank 6.Further, the water dispensed to the fourth system leading to theplurality of passages P7 is supplied to an auxiliary 110 such as aheater for warming a vehicle compartment, a thermoelectric element orthe like, where it dissipates a heat, and the resultingdropped-temperature water is discharged to the tank via a check valve111 incorporated in a passage P9.

[0038] The lower-pressure pump 7, the higher-pressure pump 8, thedispensing valve 106 and the electric motor 108 are controlled by theelectronic control unit 112 in accordance with the operational state ofthe internal combustion engine 1, the operational state of the expander4, the operational state of the auxiliary 110, the temperature of thewater in the tank 6 and the like.

[0039] The entire structure of the expander 4 will be described belowwith reference to FIGS. 2 to 6.

[0040] The expander 4 has a casing 11, which is formed of first andsecond casing halves 12 and 13 made of a metal. The first and secondcasing halves 12 and 13 form main bodies 12 a and 13 a defining a rotorchamber 14 by cooperation with each other, and circular flanges 12 b and13 b integrally with outer peripheries of the main bodies 12 a and 13 a,respectively. The circular flanges 12 b and 13 b are coupled to eachother through a metal gasket 15. An outer surface of the first casinghalf 12 is covered with a deep bowl-shaped relay chamber outer-wall 16,and a circular flange 16 a integrally connected to an outer periphery ofthe outer wall 16 is superposed on a left side of the circular flange 12b of the first casing half 12. An outer surface of the second casinghalf 13 is covered with an exhaust chamber outer-wall 17 in which amagnet coupling (not shown) for transmitting the output from theexpander 4 to the outside is accommodated, a circular flange 17 aintegrally connected an outer periphery of the outer wall 17 issuperposed on right side of the circular flange 13 b of the secondcasing half 13. The three circular flanges 12 a, 13 a 16 a and 17 a arefastened together by bolts 19 disposed circumferentially. A relaychamber 19 is defined between the relay chamber outer-wall 16 and thefirst casing half 12, and an exhaust chamber 20 is defined between theexhaust chamber-outer wall 17 and the second casing half 13. The exhaustchamber outer-wall 17 is provided with a discharge bore 17 b for guidingthe dropped-temperature and dropped-pressure vapor which has finishedits work in the expander 4.

[0041] The main bodies 12 a and 13 a of the casing halves 12 and 13 havehollow bearing tubes 12 c and 13 c protruding outwards, respectively,and a rotary shaft 21 having a hollow 21 a is rotatably supported in thehollow bearing tubes 12 c and 13 c with a pair of bearing members 22 and23 interposed therebetween. Thus, an axis L of the rotary shaft 21passes through an intersection between a longer diameter and a shorterdiameter in the rotor chamber 14 having a substantially elliptic shape.A smaller-diameter portion 21 b of a right end of the rotary shaft 21protrudes into the exhaust chamber 20 through the hollow bearing tube 13c of the second casing half 13, and a rotor boss 24 of the magnetcoupling is spline-coupled to the smaller-diameter portion 21 b. Anouter periphery of the smaller-diameter portion 21 b at the right end ofthe rotary shaft 21 and an inner periphery of the hollow bearing tube 13c of the second casing half 13 are sealed from each other by a sealmember 25, which is fixed to the inner periphery of the hollow bearingtube 13 c by a nut 26 threadedly fitted to such inner periphery.

[0042] As can be seen from FIGS. 4 and 8, a circular rotor 27 isrotatably accommodated in the rotor chamber 14 having a pseudo ellipticshape. The rotor 27 is fitted over and integrally coupled to an outerperiphery of the rotary shaft 21 by a pin 28, and an axis of the rotor27 and an axis of the rotor chamber 14 are in line with the axis L ofthe rotary shaft 21. The shape of the rotor chamber 14 as viewed in adirection of the axis L is a pseudo elliptic shape similar to a rhombicshape with four apexes rounded, and the rotor chamber 14 has a longerdiameter DL and a shorter diameter DS. The shape of the rotor 27 asviewed in the direction of the axis L is a true circular shape and has adiameter DR slightly smaller than the shorter diameter DS of the rotorchamber 14.

[0043] Both of the sectional shapes of the rotor chamber 14 and therotor 27 as viewed in a direction perpendicular to the axis L aresimilar to a field competition track. More specifically, the sectionalshape of the rotor chamber 14 is formed from a pair of flat faces 14 a,14 a extending in parallel to each other at a distanced lefttherebetween, and an arcuate face 14 b having a center angle of 180° andsmoothly connecting outer peripheries of the flat faces 14 a, 14 a toeach other, and the sectional shape of the rotor 27 is formed from apair of flat faces 27 a, 27 a extending in parallel to each other at adistance d left therebetween, and an arcuate face 27 b having a centerangle of 180° and smoothly connecting outer peripheries of the flatfaces 27 a, 27 a to each other. Therefore, the flat faces 14 a, 14 a ofthe rotor chamber 14 and the flat faces 27 a, 27 a of the rotor 27 arein contact with each other, and a pair of spaces (see FIG. 4) forming acrescent shape are defined between the inner peripheral surface of therotor chamber 14 and the outer peripheral surface of the rotor 27.

[0044] The structure of the rotor 27 will be described below in detailwith reference to FIGS. 3, 6, 9 and 10.

[0045] The rotor 27 is formed of a rotor core 31 fixed to the outerperiphery of the rotary shaft 21, and twelve rotor segments 32 fixed tocover the periphery of the rotor core 31 and forming an outer profile ofthe rotor 27. The rotor core 31 includes a disk-shaped main body 31 a,and a gear-shaped boss portions 31 b, 31 b protruding in axiallyopposite directions from a central portion of the main body 31 a. Twelvecylinders 33 made of a ceramic (or carbon) are mounted radially atdistances of 30° to the main body 31 a and fixed thereto by caps 34 andkeys 35, so that they are prevented from being withdrawn. Asmaller-diameter portion 33 a is projectingly provided at an inner endof each of the cylinders 33, and a base end of the smaller-diameterportion 33 a and the main body 31 a of the rotor core 31 are sealed fromeach other through an O-ring 36. A tip end of the smaller-diameterportion 33 a is fitted over the outer peripheral surface of the hollowrotary shaft 21, and cylinder bores 33 b communicate with the hollow 21a in the rotary shaft 21 through twelve third vapor passages S3extending through the smaller-diameter portions 33 a and the rotaryshaft 21. A piston 37 made of a ceramic is slidably received in each ofthe cylinders 33. When the piston 37 is moved to a radially innermostlocation, it is retracted and sunk completely in the cylinder bore 33 b,and when the piston 37 is moved to a radially outermost location, abouthalf of the entire length thereof protrudes to the outside of thecylinder bore 33 b.

[0046] Each of the rotor segments 32 is formed of five componentscoupled to one another. The five components are a pair of block members38, 38 having hollows 38 a, 38 a, a pair of side plates 39, 39 made ofU-shaped plate materials, and a bottom plate 40 made of a rectangularplate material. These components are integrally connected to one anotherby brazing.

[0047] Two recess s 38 b and 38 c are defined in an outer peripheralsurface of each of the block members 38, namely, a surface opposed tothe pair of flat faces 14 a, 14 a of the rotor chamber 14 to extend inan arcuate shape about the axis L, and lubricating water ejection bores38 d, 38 c open into central portions of the recesses 38 b and 38 c,respectively. A twentieth water passage W20 and a twenty first waterpassage W21 are provided in a recessed manner in a face of the blockmember 38, which is coupled to the side plate 39.

[0048] An orifice-defined member 41 having twelve orifices is fittedinto a central portion of the bottom plate 40, and an O-ring 42 mountedto the bottom plate 40 to surround the orifice-defined member 41 sealsthe orifice-defined member 41 and the outer peripheral surface of themain body 31 a of the rotor core 31 from each other. Fourteenth tonineteenth water passages W14 to W19 are provided two by two in arecessed manner in a surface of the bottom plate 40 coupled to the blockmember 38 to extend radially from the orifice-defined member 41. Thefourteenth to nineteenth water passages W14 to W19 extend toward thesurface coupled to the side plate 39.

[0049] Twenty second to twenty sixth water passages W22 to W27 areprovided in a recessed manner in a surface of each side plate 39 coupledto the block members 38, 38 and the bottom plate 40. The fourteenthwater passage W14, the fifteenth water passage W15, the eighteenth waterpassage W18 and the nineteenth water passage W19 in an outer area of thebottom plate 40 communicate with the twenty second water passage W22,the twenty third water passage 23, the twenty sixth water passage W26and the tw nty seventh water passage W27 in the side plate 39, and thesixteenth water passage W16 and the seventeenth water passage W27 in aninner area of the bottom plate 40 communicate with the twenty fourthwater passage W24 and the twenty fifth water passage W25 in the sideplate 39 through the twentieth water passage W20 and the twenty firstwater passage W21 in the block member 38. Outer ends of the twentysecond water passage W22, the twenty fifth water passage W25, the twentysixth water passage W26 and the twenty seventh water passage W27 in theside plate 39 open as four lubricating water ejection bores 39 a intothe outer surface of the side plate 39. Outer ends of the twenty thirdwater passage W23 and the twenty fourth water passage W24 in the sideplate 39 communicate with the lubricating oil ejection bores 38 d and 38e in the recesses 38 b and 38 c through a twenty eighth water passageW28 and a twenty ninth water passage W29 defined in each of the blockmembers 38, 38, respectively. A notch 39 b having a partially arcuatesection is formed in the outer surface of the side plate 39 in order toavoid the interference with the piston 37 moved radially outwards. Thereason why the twentieth water passage W20 and the twenty first waterpassage W21 are defined in the block member 38 rather than in the sideplate 39 is that the side plate 39 has a thickness decreased byprovision of the notch 39 b, and a thickness enough to define thetwentieth water passage W20 and the twenty first water passage W21can beensured in the block member 38.

[0050] As shown in FIGS. 2, 5, 9 and 11, twelve vane grooves 43 aredefined between the adjacent rotor segments 32 of the rotor 27 to extendradially, and plate-shaped vanes 44 are slidably received in the vanegrooves 43, respectively. Each of the vanes 44 is formed into asubstantially U-shape and includes parallel faces 44 a, 44 a extendingalong the parallel faces 14 a, 14 a of the rotor chamber 14, an arcuateface 44 b extending along the arcuate face 14 b of the rotor chamber 14,and a notch 44 c located between the parallel faces 44 a, 44 a. Rollers45, 45 having a roller bearing structure are rotatably supported on apair of support shafts 44 d, 44 d protruding from the parallel faces 44a, 44 a, respectively.

[0051] A seal member 46 made of a synthetic resin and formed into aU-shape is retained on the arcuate face 44 b of the vane 44, and has atip end protruding slightly from the arcuate face 44 b of the vane 44 tocome into sliding contact with the arcuate face 14 b of the rotorchamber 14. Sliding members 47, 47 made of a synthetic resin are fixedto the parallel faces 44 a, 44 a of the vane 44 to come into slidingcontact with the parallel faces 14 a, 14 a of the rotor chamber 14.Sliding members 48, 48 of a synthetic resin are also fixed to oppositesides of the notch 44 c of the vane 44 to come into sliding contact withthe main body 31 a of the rotor core 31. Two recesses 44 e, 44 e aredefined in each of opposite sides of the vane 44 and opposed to radiallyinner two of the four lubricating water ejection bores 39 a opening intothe outer surfaces of the side plates 39, 39 of the rotor segment 32. Aprojection 44 f provided at a central portion of the notch 44 c of thevane 44 in a protruding manner to face radially inwards abuts against aradially outer end of the piston 37. A water discharge passage 44 g isdefined in the vane to extend radially, and opens at its radially innerend into a tip end of the projection 44 f and at its radially outer endinto one of sides of the vane 44. A location at which the waterdischarge passage 44 g opens into the one side of the vane 44 faces to apoint radially outer than the arcuate face 27 b of the rotor 27, whenthe vane 44 is moved to protrude to the radially outermost position.

[0052] Annular grooves 49, 49 having a pseudo elliptic shape similar toa rhombic shape with four apexes rounded are provided in a recessedmanner in the flat faces 14 a, 14 a of the rotor chamber 14 defined bythe first and second casing halves 12 and 13, and the pair of rollers45, 45 of each of the vanes 44 are rollably engaged in the annulargrooves 49, 49. The distance between each of the annular grooves 49, 49and the arcuate face 14 b of the rotor chamber 14 is constant over theentire periphery. Therefore, when the rotor 44 is rotated, the vane 44with the rollers 45, 45 guided in the annular grooves 49, 49 isreciprocally moved radially within the vane groove 43 and slid along thearcuate face 14 b of the rotor chamber 14 in a state in which the sealmember 46 mounted to the arcuate face 44 b of the vane 44 has beencompressed at a given amount. Thus, it is possible to reliably seal thevane chambers 50 defined between the adjacent vanes 44, while preventingthe rotor chamber 14 and the vanes 44 from being brought into directsolid contact with each other to prevent an increase in slidingresistance and the occurrence of the wearing.

[0053] A pair of circular seal grooves 51, 51 are defined in the flatfaces 14 a, 14 a of the rotor chamber 14 to surround the outer sides ofthe annular grooves 49, 49. A pair of ring seals 52 each having twoO-rings 52 and 53 are slidably received in the circular seal grooves 51,respectively, and have sealing faces opposed to the recesses 38 b and 38c defined in each of the rotor segments 32. The pair of ring seals 54,54 are prevented from being turned relative to the first and secondcasing halves 12 and 13 by knock pins 55, 55, respectively.

[0054] The assembling of the rotor 27 is carried out in the followingmanner: In FIG. 9, the twelve rotor segments 32 are fitted over theouter periphery of the rotor core 31 having the cylinders 33, the caps34 and the keys 35 previously assembled thereto, and the vanes 44 arefitted into the twelve vane grooves 43 defined between the adjacentrotor segments 32. At this time, a shim having a predetermined thicknessis disposed on each of opposite sides of each vane 44 in order to definea clearance between each of the vanes 44 and each of the side plates 39of the rotor segments 32. In this state, the rotor segments 32 and thevanes 44 are tightened radially inwards to the rotor core 31 using ajig, and the rotor segments 32 are positioned accurately relative to therotor core 31. Thereafter, the rotor segments 32 are temporarily fixedto the rotor core 31 by temporarily fixing bolts 58 (see FIG. 2). Then,the rotor 27 is removed from the jig, and the pinholes 56, 56 are madein each of the rotor segments 32 to extend through the rotor core 31.The knock pins 57, 57 are press-fitted into the pinholes 56, 56, wherebyrotor segments 32 are coupled to the rotor core 31.

[0055] As can be seen from FIGS. 3, 7 and 12, the pair of bearingmembers 22 and 23 supporting the outer peripheral surface of the rotaryshaft 21 has an inner peripheral surface which is tapered, so that itsdiameter is increased toward the rotor 27. The axially outer ends of thebearing members 22 and 23 are engaged in the hollow bearing tubes 12 cand 13 c of the first and second casing halves 12 and 13, so that theyare prevented from being turned. It should be noted that the outerperiphery at the left and of the rotary shaft 21 supported in the lefthollow bearing tube 12 c is constituted by a different member 21 c inorder to enable the assembling of the rotor 27 to the rotary shaft 21.

[0056] An opening 16 b is defined in the center of the relay chamberouter-wall 16, and a boss portion 61 a of a valve housing 61 disposed onthe axis L is fixed to an inner surface of the opening 16 b by aplurality of bolts 62 and also fixed to the first casing half 12 by anut 63. A cylindrical first fixing shaft 64 is relatively rotatablyfitted in the hollow 21 a in the rotary shaft 21, and a second fixingshaft 65 is coaxially fitted to an inner periphery of a right end of thefirst fixing shaft 64. An outer peripheral portion of a right end of thesecond fixing shaft 65 protruding from the first fixing shaft 64 and thehollow 21 a in the rotary shaft 21 are sealed from each other by anO-ring 66. The valve housing 61 extending within the first fixing shaft64 includes a flange 61 b, and an O-ring 67, a thickened portion 64 a ofthe first fixing shaft 64, an O-ring 68, a washer 69, a nut 70 and thesecond fixing shaft 65 are fitted sequentially at the right of theflange 61 b. The nut 70 and the second fixing shaft 65 are threadedlycoupled to the valve housing 61 and hence, the thickened portion 64 a ofthe first fixing shaft 64 is positioned between the flange 61 b of thevalve housing 61 and the washer 69 with the pair of O-rings 66 and 67interposed therebetween.

[0057] The first fixing shaft 64 supported on the inner periphery of thehollow bearing tube 12 c of the first casing half 12 with an O-ring 71interposed therebetween is connected at its left end to the boss portion61 a of the valve housing 61 by a ring-shaped Oldham coupling 72, andthe deflection of the rotor 27 supported on the outer periphery of thefirst fixing shaft 64 through the rotary shaft 21 can be permitted bypermitting the radial deflection of the first fixing shaft 64 by theOldham coupling 72. In addition, the first fixing shaft. 64 is preventedfrom being turned relative to the casing 11 by fixing arms 73 a, 73 a ofa detent member 73 loosely fitted in the left end of the first fixingshaft 64 to the first casing half 12 by bolts 74, 74.

[0058] A vapor supply pipe 75 is fitted within the valve housing 61disposed on the axis L and is fixed to the valve housing 61 by a nut 76.The vapor supply pipe 75 is connected at its right end to a nozzlemember 77 press-fitted into the valve housing 61. A pair of recesses 81,81 (see FIG. 7) are defined at a phase difference of 180° astride thevalve housing 61 and a tip end of the nozzle member 77, and annularjoint members 78, 78 are fitted into and retained in the recesses 81,81. A first vapor passage S1 is defined axially in the center of thenozzle member 77 to lead to the vapor supply pipe 75, and a pair ofsecond vapor passages S2, S2 are provided at a phase difference of 180°to extend axially through the thickened portion 64 a of the first fixingshaft 64. A terminal end of the first vapor passage S1 and radiallyinner ends of the second vapor passages S2, S2 are always incommunication with each other through the joint members 78, 78. Twelvethird vapor passages S3 are provided to extend through the rotary shaft21 and the smaller-diameter portions 33 a of the twelve cylinders 33retained at the distances of 30° in the rotor 27 fixed to the rotaryshaft 21, as described above. Radially inner ends of the third vaporpassages S3 are opposed to radially outer ends of the second vaporpassage S2, S2 to be able to communicate with them.

[0059] A pair of notches 64 b, 64 b are defined at a phase diff rence of180° in the outer peripheral surface of the thickened portion 64 a ofthe first fixing shaft 64, and are capable of communicating with thethird vapor passages S3. The notches 64 b, 64 b he relay chamber 19communicate with each other through a pair of fourth vapor passages S4,S4 defined obliquely in the first fixing shaft 64, a fifth vapor passageS5 defined axially in the first fixing shaft 64, a sixth vapor passageS6 defined in the boss portion 61 a of the valve housing 61 andthrough-bores 61 c which open into an outer periphery of the bossportion 61 a of the valve housing 61.

[0060] As shown in FIG. 5, a plurality of intake ports 79 are defined ina radial arrangement in the first casing half 12 at locations advancedat an angle of 15° in a direction of rotation of the rotor 27, based ona direction of the shorter-diameter of the rotor chamber 14. Theinternal space in the rotor chamber 14 communicates with the relaychamber 19 by virtue of the intake ports 79. A large number of exhaustports 80 are provided and arranged in a plurality of radial arrays inthe second casing half 13 at locations delayed at an angle of 15° to 75°in the direction of rotation of the rotor 27, based on the direction ofthe shorter-diameter of the rotor chamber 14. The internal space in therotor chamber 14 communicates with the exhaust chamber 20 by virtue ofthe exhaust ports 80.

[0061] A rotary valve V is formed to permit the periodical communicationof the second vapor passages S2, S2 and the third vapor passages S3 witheach other as well as the periodical communication of the notches 64 b,64 b in the first fixing shaft 64 and the third vapor passages S3 witheach other by relative rotation of the first fixing shaft 64 and therotary shaft 21.

[0062] As can be seen from FIGS. 2 and 3, pressure chambers 86, 86 aredefined in backs of the ring seals 54, 54 fitted in the circular sealgrooves 51, 51 in the first and second casing halves 12 and 13, and afirst water passage W1 defined in the first and second casing halves 12and 13 communicates with both of the pressure chambers 86, 86 through asecond water passage W2 and a third water passage W each forming a pipe.A filter chamber 13 d capable of being opened and closed by a cover 89provided with two O-rings 87 and 88 is defined radially outside thehollow bearing tube 13 c of the second casing half 13, and an annularfilter 90 is accommodated in the filter chamber 13 d. The first waterpassage W1 in the second casing half 13 communicates with an outerperipheral surface of the filter 90 through a fourth water passage W4forming a pipe, and an inner peripheral surface of the filter 90communicates with a sixth annular water passage W6 defined between thesecond casing half 13 and the rotary shaft 21 through a fifth waterpassage W5 defined in the second casing half 13. The sixth water passageW6 communicates with the twelve orifice-defined members 41 throughtwelve seventh water passages W7 extending axially within the rotaryshaft 21, an annular groove 21 d defined in the outer periphery of therotary shaft 21 and twelve eighth water passages W8 extending radiallywithin the rotor core 31, respectively.

[0063] The annular groove 21 d defined in the outer periphery of therotary shaft 21 communicates with an annular groove 21 e defined in theouter periphery of the rotary shaft 21 through twelve ninth waterpassages W9 (see FIG. 7) extending axially, and the annular groove 21 ecommunicates with an eleventh annular water passage W11 defined betweenthe left end of the rotary shaft 21 and the first housing half 12through twelve tenth water passages W10 extending axially within therotary shaft 21. The sixth annular water passage W6 and the eleventhannular water passage W11 communicate with sliding surfaces between theinner peripheries of the bearing members 22 and 23 and the outerperiphery of the rotary shaft 21 through orifices around outerperipheries of orifice-defining bolts 91 threadedly fitted in thebearing members 22 and 23 and further via twelfth water passages W12defined in the bearing members 22 and 23. The sliding surfaces betweenthe inner peripheries of the bearing members 22 and 23 and the outerperiphery of the rotary shaft 21 communicate with the vane grooves 43via thirteenth draining water passages W13.

[0064] The sixth annular water passage W6 communicates with slidingportions between the inner peripheral surface of the hollow 21 a in therotary shaft 21 and the outer peripheral surface of the right end of thefirst fixing shaft 64 via two thirtieth water passages W30, W30 providedaxially in the rotary shaft 21. A seal groove 64 c defined at the rightof the thickened portion 64 a of the first fixing shaft 64 communicateswith the fifth vapor passage S5 through thirty first water passages W31,W31 provided obliquely in the first fixing shaft 64. The eleventhannular water passage W11 communicates with sliding portions between theinner peripheral surface of the hollow 21 a in the rotary shaft 21 andthe outer peripheral surface of the left end of the first fixing shaft64, and a seal groove 64 d defined at the left of the thickened portion64 a of the first fixing shaft 64 communicates with the fifth vaporpassage S5 through thirty second water passages S32, W32 extendingradially through the first fixing shaft 64 and the thirty first waterpassages W31, W31.

[0065] As can be seen from the comparison of FIGS. 1 and 2 with eachother, the high-temperature and high-pressure vapor from the evaporator3 is supplied via the passage P4 to the vapor supply pipe 75 for theexpander 4; the vapor from the reducing valve 107 located downstream ofthe dispensing valve 106 is supplied via the passage P5 into the relaychamber 19 in the expander 4, and the high-temperature water from thedispensing valve 106 is supplied via the passage P6 to the first waterpassage W1; the dropped-temperature and dropped-pressure vapor from thedischarge bore 17 b in the expander 4 is discharged to the passage P8.

[0066] The operation of the present embodiment having theabove-described arrangement will be described below.

[0067] First, the operation of the expander 4 will be described.Referring to FIG. 3, the high-temperature and high-pressure vapor fromthe passage P4 leading to a downstream side of the evaporator 3 issupplied to the vapor supply pipe 75, the first vapor passage S1 definedaxially in the nozzle member 77 and the pair of second vapor passagesS2, S2 extending radially through the nozzle member 77, the jointmembers 78, 78 and the thickened portion 64 a of the first fixing shaft64. Referring to FIGS. 6 and 7, when the rotary shaft 21 rotated inunison with the rotor 27 reaches a predetermined phase, the pair ofthird vapor passages S3, S3 existing at the locations advanced in thedirection of rotation of the rotor 27 shown by an arrow R from a shorterdiameter position of the rotor chamber 14 are put into communicationwith the pair of second vapor passages S2, S2, whereby thehigh-temperature and high-pressure vapor in the second vapor passagesS2, S2 is supplied into the pair of cylinders 33, 33 via the third vaporpassages S3, S3 to urge the pistons 37, 37 radially outwards. When thevanes 44, 44 urged by the pistons 37, 37 are moved radially outwards,the advancing movements of the pistons 37, 37 are converted into therotational movement of the rotor 27 by the engagement of the pair ofrollers 45, 45 mounted on the vanes 44, 44 and the annular grooves 49,49 with each other.

[0068] Even after the communication between the second vapor passagesS2, S2 and the third vapor passages S3, S3 is blocked with the rotationof the rotor 27 in the direction indicated by the arrow R, the pistons37, 37 are further advanced by the further continuation of the expansionof the high-temperature and high-pressure vapor within the cylinders 33,33, whereby the rotation of the rotor 27 is continued. When the vanes44, 44 reach a longer-diameter position of the rotor chamber 14, thethird vapor passages S3, S3 leading to the corresponding cylinders 33,33 are put into communication with the notches 64 b, 64 b of the firstfixing shaft 64, and the pistons 37, 37 urged by the vanes 44, 44 withthe rollers 45, 45 guided in the annular grooves 49, 49 are movedradially inwards, whereby the vapor in the cylinders 33, 33 is passedthrough the third vapor passages S3, S3, the notches 64 b, 64 b, thefourth vapor passages S4, S4, the fifth vapor passage S5, the sixthvapor passage S6 and the through-bores 61 c and supplied as a firstdropped-temperature and dropper-pressure vapor into the relay chamber19. The first dropped-temperature and dropper-pressure vapor is a vaporresulting from the high-temperature and high-pressure vapor which hasbeen supplied from the vapor supply pipe 75 and has finished its workfor driving the pistons 37, 37, resulting in its temperature andpressure dropped. The own heat energy and the pressure energy of thefirst dropped-temperature and dropper-pressure vapor are reduced, ascompared with those of the high-temperature and high-pressure vapor, butare still sufficient to drive the vanes 44.

[0069] The vapor is supplied from the reducing valve 107 locateddownstream of the dispensing valve 106 via the passage P5 to the relaychamber 19, where it is joined and mixed homogeneously with the firstdropped-temperature and dropped-pressure vapor.

[0070] The first dropped-temperature and dropped-pressure vapor and thevapor from the dispensing valve 106 mixed in the relay chamber 19 aresupplied from the intake ports 79 in the first casing half 12 into thevane chambers 50 in the rotor chamber 14, namely, the space defined bythe rotor chamber 14, the rotor 27 and the pair of adjacent vanes 44,44, where the vapor is expanded to rotate the rotor 27. A seconddropped-temperature and dropped-pressure vapor resulting from the firstdropped-temperature and dropped-pressure vapor finishing its work,resulting in its temperature and pressure dropped, is discharged fromthe exhaust ports 80 in the second casing half 13 into the exhaustchamber 20 and supplied therefrom via the discharge bore 17 b into thecondenser 5.

[0071] In this manner, the twelve pistons 37 are operated sequentiallyby the expansion of the high-temperature and high-pressure vapor torotate the rotor 27 through the rollers 45, 45 and the annular grooves49, 49, and an output is produced from the rotary shaft 21 by rotatingthe rotor 27 through the vanes 44 by the expansion of the firstdropped-temperature and dropped-pressure vapor resulting from thedropping in temperature and pressure of the high-temperature andhigh-pressure vapor and the expansion of the vapor from the dispensingvalve 106.

[0072] The lubrication of various sliding portions of the expansion 4 bythe water will be described below. The lubricating water is suppliedfrom the dispensing valve 106 via the passage P6 to the first waterpassage W1 in the casing 11.

[0073] The water supplied to the first water passage W1 is supplied viathe second water passage W2 and the third water passage each forming apipe to the pressure chambers 86, 86 in the bottoms of the circular sealgrooves 51, 51 in the first casing half 12 and the second casing half13, thereby biasing the ring seals 54, 54 toward the side of the rotor27. The water supplied from the first water passage W1 to the fourthwater passage W4 forming the pipe, after being filtered by the filter 90to remove a foreign matter, is supplied to the fifth water passage W5defined in the second casing half 13, the sixth water passage W6 definedbetween the second casing half 13 and the rotary shaft 21, the seventhwater passages W7 defined within the rotary shaft 21, the annular groove21 d in the rotary shaft 21 and the eighth water passages W8 defined inthe rotor core 31, where the water is further pressurized by thecentrifugal force produced with the rotation of the rotor 27 and thensupplied to the orifice-defined members 41 of the rotor segments 32.

[0074] In each of the rotor segments 32, the water flowing through theorifice-defined member 41 into the fourteenth water passage 14 in thebottom plate 40 is passed through the twenty second water passage W22 inthe side plate 39 and ejected from the lubricating water ejection bores39 a, and the water flowing through the orifice-defined member 41 intothe seventeenth water passage W17 in the bottom plate 40 is passedthrough the twenty first water passage W21 in the block member 38 andthe twenty fifth water passage W25 in the side plate 39 and ejected fromthe lubricating water ejection bores 39 a. The water flowing through theorifice-defined member 41 into the eighteenth water passage W18 in thebottom plate 40 is passed through the twenty sixth water passage W26 inthe side plate 39 and ejected from the lubricating water ejection bores39 a, and the water flowing through the orifice-defined member 41 intothe nineteenth water passage W19 in the bottom plate 40 is passedthrough the twenty seventh water passage W27 in the side plate 39 andejected from the lubricating water ejection bores 39 a. Lower two of thefour lubricating water ejection bores 39 a opening into the surface ofthe side plate 39 communicate with the insides of the recesses 44 e, 44e in the two vanes 44.

[0075] The water flowing through the orifice-defined member 41 into thefifteenth water passage W15 in the bottom plate 40 is passed through thetwenty third water passage W23 in the side plate 39 and the twenty ninthwater passage W29 in the block member 38 and ejected from thelubricating water ejection bore 38 e within the recess 38 c, and thewater flowing through the orifice-defined member 41 into the sixteenthwater passage W16 in the bottom plate 40 is passed through the twentiethwater passage W20 in the block member 38, the twenty fourth waterpassage W24 in the side plate 39 and the twenty eighth water passage W28in the block member 38 and ejected from the lubricating water ejectionbore 38 d within the recess 38 b.

[0076] The water ejected from the lubricating water ejection bores 39 ain the side plate 39 of each of the rotor segments 32 into the vanegroove 43 forms a static pressure bearing between the vane groove 43 andthe vane 44 slidably fitted in the vane groove 43 to support the vane 44in a floated state, thereby preventing the solid contact of the sideplate 39 of the rotor segment 32 and the vane 44 with each other toprevent the occurrences of the seizure and the wearing. By supplying thewater for lubricating the sliding surface of the vane 33 through theeighth water passage W8 provided radially in the rotor 27 in the abovemanner, the water can be pressurized by the centrifugal force, but alsothe temperature around the rotor 27 can be stabilized to reduce theinfluence due to the thermal expansion, and the set clearance can bemaintained to suppress the leakage of the vapor to the minimum.

[0077] A circumferential load applied to each of the vanes 44 (a load ina direction perpendicular to the plate-shaped vane 44) is a resultantforce derived from a load due to a difference between vapor pressuresapplied to the front and rear surfaces of the vane within the rotorchamber 14 and circumferential components of reaction forces receivedfrom the annular grooves 49, 49 by the rollers 45, 45 mounted on thevane 44, but these loads are varied periodically depending on the phaseof the rotor 27. Therefore, the vane 44 receiving such unbalanced loadperiodically shows such a behavior that it is inclined within the vanegroove 43.

[0078] If the vane 44 is inclined by the unbalanced load in this manner,the clearance between the vane 44 and the four lubricating waterdischarge bores 39 a opening into the side plates 39, 39 of the rotorsegments 32 on opposite sides of the vane 44 is varied and hence, thewater film in the widened portion of the clearance is carried away, andit is difficult for the water to be supplied into the narrowed portionof the clearance. For this reason, there is a possibility that thepressure is not built up at the sliding portions, whereby the vane 44 isbrought into direct contact with the sliding surfaces of the side plates39, 39 to become worn. According to the present embodiment, however, thewater is supplied through the orifices into the lubricating waterdischarge bores 39 a by the orifice-defined member 41 mounted on therotor segment 32 and hence, the above-described disadvantage isovercome.

[0079] More specifically, when the clearance between the lubricatingwater discharge bores 39 a and the vane 44 is widened, the pressure ofwater supplied is constant and hence, the flow rate of the water isincreased by an increase in amount of water flowing out of the clearancerelative to a constant pressure difference produced across the orificein a steady state, whereby the pressure difference across the orifice isincreased by virtue of an orifice effect, leading to a reduction in thepressure in the clearance, and as a result, a force for narrowing thewidened clearance back to the original width is generated. When theclearance between the lubricating water discharge bores 39 a and thevane 44 is narrowed, the amount of water flowing out of the clearance isreduced, leading to a reduction in pressure difference across theorifice, and as a result, a force for widening the clearance narroweddue to the in crease in pressure in the clearance back to the originalwidth is generated.

[0080] Even if the clearance between the lubricating water dischargebores 39 a and the vane 44 is varied by the load applied to the vane 44,as described above, the orifices automatically regulate the pressure ofthe water supplied to the clearance depending on the variation in sizeof the clearance and hence, the clearance between the vane 44 and eachof the side plates 39, 39 of the rotor segments 32 on the opposite sidesof the vane 44 can be maintained at a desired size. Thus, the water filmcan be always retained between the vane 44 and each of the side plates39, 39 to support the vane in the floated state, thereby reliablyavoiding that the vane 44 is brought into solid contact with the slidingsurface of each of the side plates 39, 39 to become worn.

[0081] In addition, the water is retained in each of the two recesses 44e, 44 e defined in each of the opposite surfaces of the vane 44 andhence, each of the recesses 44 e, 44 e serves as a pressure dam tosuppress a drop in pressure due to the leakage of the water. As aresult, the vane 44 clamped between the sliding surfaces of the pair ofside plates 39, 39 is brought into the floated state by means of thewater, whereby the sliding resistance can be decreased to near zero.When the vane 44 is moved reciprocally, the radial position of the vane44 relative to the rotor 27 is changed, but the vane 44 movedreciprocally can be always retained in the floated state to effectivelyreduce the sliding resistance, because the recesses 44 e, 44 e areprovided in the vane 44 rather than in the side plates 39, 39 andprovided in the vicinity of the rollers 45, 45 with the load appliedmost largely to the vane, 44.

[0082] The water which has lubricated the sliding surfaces of the vaneon the side plates 39, 39 is moved radially outwards by the centrifugalforce to lubricate the sliding portions of the seal member 46 mounted onthe arcuate face 44 b of the vane 44 and the arcuate face 14 b of therotor chamber 14. The water which has finished the lubrication isdischarged from the rotor chamber 14 through the exhaust ports 80 intothe exhaust chamber 20.

[0083] Portions of the water flowing into the rotor chamber 14 afterlubricating the sliding surfaces of the side plate 39, 39 and the vane44, which flow into the vane chambers 50 in an expansion stroke in therotor chamber 14, are mixed with the high-temperature vapor andevaporated, thereby increasing the output from the expander 4.

[0084] The axis of abscissas in a graph shown in FIG. 13 is the timing(phase) for supplying the eater to the vane chamber 50, and the axis ofordinates is the amount of increment in output from the expander 4. Inaddition, the pressure of water supplied to the vane chamber 50 throughthe sliding surfaces is 2 MPa, and the percent of the amount of watersupplied to the vane chamber 50 through the sliding surfaces, to theamount of water supplied from the evaporator 3 via the passage P4 to thevane chamber 50 in the expander 4, is 60%. Shown in FIG. 13 are curvesin cases where the temperature of the water supplied to the vane chamber50 through the sliding surfaces is 50° C., 100° C. and 200° C. It can beseen from FIG. 13 that as the higher the temperature of the water, themore the amount of the output from the expander 4 is increased, and themore the phase, in which the mount of increment in output assumes apeak, is fastened.

[0085] The axes of abscissas and ordinates in a graph shown in FIG. 14are the same as in FIG. 13. Shown in Fiug.14 are curves in cases wherethe percent of the amount of water supplied to the vane chamber 50through the sliding surfaces, to the amount of water supplied from theevaporator 3 via the passage P4 to the vane chamber 50 in the expander4, is 0%, 20%. 40% and 60%. In this case, the pressure of the watersupplied to the vane chamber 50 through the sliding surfaces is 2 MPa,and the temperature of such water is constant. It can be seen that ifthe percent of the amount of the water supplied to the vane chamber 50through the sliding surfaces is increased, the amount of increment inoutput from the expander 4 is increased, but the phase in which in whichthe mount of increment in output assumes a peak is always constantwithout being varied.

[0086] As described above, the water is supplied to the pressurechambers 86, 86 in the bottoms of the circular seal grooves 51, 51 inthe first casing half 12 and the second casing half 13 to bias the ringseals 54, 54 toward the side of the rotor 27, and the water is ejectedfrom the lubricating water ejection bores 38 d and 38 e defined withinthe recesses 38 b and 38 c in each of the rotor segments 32 to form thestatic pressure bearing on the sliding surface on the flat faces 14 a,14 a of the rotor chamber 14, whereby the flat faces 27 a, 27 a of therotor 27 can be sealed by the ring seals 54, 54 which are in the floatedstate within the circular seal grooves 51, 51. As a result, the vapor inthe rotor chamber 14 can be prevented from being leaked through theclearance between the rotor chamber 14 and the rotor 27. At this time,the ring seals 54, 54 and the rotor 27 are isolated from each other bythe water films supplied from the lubricating water ejection bores 38 dand 38 e, so that they cannot be brought into solid contact with eachother. In addition, even if the rotor 27 is inclined, the ring seals 54,54 within the circular seal grooves 51, 51 are inclined, following theinclination of the rotor 27, whereby the stable sealing performance canbe ensured, while suppressing the frictional force to the minimum.

[0087] The water which has lubricated the sliding portions of the ringseals 54, 54 and the rotor 27 is supplied to the rotor chamber 14 by thecentrifugal force and discharged therefrom via the exhaust ports 80 tothe outside of the casing 11.

[0088] On the other hand, the water supplied from the sixth waterpassage W6 flows via the orifices defined around the outer peripheriesof the orifice-defining bolts 91 in the bearing member 23 and thetwelfth water passages 12 to form the water film on sliding surfaces ofthe inner periphery of the bearing member 23 and the outer periphery ofthe rotary shaft 21 to support the outer periphery of a right half ofthe rotary shaft 21 in the floated state by the water film, therebylubricating the sliding surfaces in such a manner that the solid contactof the rotary shaft 21 and the bearing member 23 with each other isprevented to prevent the occurrences of the seizure and the wearing. Thewater supplied from the sixth water passage W6 to the seventh waterpassages W7, the ninth water passages W9, the tenth water passages W10and the eleventh water passage W11 defined in the rotary shaft 21 flowsvia the orifices defined around the outer peripheries of theorifice-defining bolts 91 in the bearing member 22 and the twelfth waterpassages W12 to form the water film on sliding surfaces of the innerperiphery of the bearing member 22 and the outer periphery of the rotaryshaft 21 to support the outer periphery of a left half of the rotaryshaft 21 in the floated state by the water film, thereby lubricating thesliding surfaces in such a manner that the solid contact of the rotaryshaft 21 and the bearing member 23 with each other is prevented toprevent the occurrences of the seizure and the wearing. The water whichhas lubricated the sliding surfaces of the bearing members 22 and 23 isdischarged via the thirteenth water passages W13 defined within thebearing members 22 and 23 into the vane grooves 43.

[0089] The water accumulated in the vane grooves 43 flows into the waterdischarge passages 44 g connecting the bottoms of the vanes 44 withone-sides of the vanes 44, but because the water discharge passages 44 gopen into the rotor chamber 14 in a predetermined angle range where thevanes 44 protrude most largely from the rotor 27, the water in the vanegrooves 43 is discharged via the water discharge passages 44 g into therotor chamber 14 under the action of a difference in pressure betweenthe vane grooves 43 and the rotor chamber 14.

[0090] The water supplied from the sixth water passage W6 via thethirtieth water passage W30 defined in the rotary shaft 21 lubricatesthe outer periphery of the first fixing shaft 64 and the right half ofthe sliding surface on the inner periphery of the rotary shaft 21, andis then discharged from the seal groove 64 c in the first fixing shaft64 via the thirty first water passages W31, W31 to the fifth vaporpassage S5. Further, the water from the eleventh water passage W11lubricates the outer periphery of the first fixing shaft 64 and the lefthalf of the sliding surface on the inner periphery of the rotary shaft21, and is then discharged from the seal groove 64 d in the first fixingshaft 64 via the thirty first water passage W31 to the fifth vaporpassage S5.

[0091] As described above, the rotor 27 of the expander 4 is constitutedin a divided manner by the rotor core 31 and the plurality of rotorsegments 32 and hence, the dimensional accuracy of the vane grooves 43in the rotor 27 can be enhanced easily. In the simple rotor 27, it isextremely difficult to make the vane grooves 43 with a groove widthhaving a good accuracy to enhance the surface roughness of the slidingsurface, but such problem can be solved by assembling the plurality ofpreviously fabricated rotor segments to the rotor core 31. Moreover,even if an error is accumulated due to the assembling of the pluralityof rotor segments 32, the accumulation of error can be absorbed byregulating the size of last one of the rotor segments 32, therebyfabricating the rotor 27 having a high accuracy as a whole.

[0092] The inner rotor core 31 to which the high-temperature andhigh-pressure vapor is supplied and each of the outer rotor segments 32relatively low in temperature are formed by the different members.Therefore, the transmission of heat from the rotor core 31 having thehigh temperature to the rotor segments 32 can be suppressed, whereby thedissipation of heat to the outside of the rotor 27 can be prevented toenhance the thermal efficiency, but also the thermal deformation of therotor 27 can be moderated to enhance the accuracy. Moreover, a materialand a processing method suitable for each of the functions of the rotorcore 31 and the rotor segments 32 can be selected and hence, the degreeof freedom of the design and the degree of freedom of the processingmethod are increased, and the alleviation of the wearing of the slidingsurfaces of the rotor segments 32 and the vanes 44, an enhancement indurability and an enhancement in sealability can be achieved. Further,even when a disadvantage is arisen in a portion of the rotor 27, therotor 27 can be repaired only by replacing such portion by a newportion. This can contribute to a reduction in cost, as compared with acase where the entire rotor is replaced by a new rotor, or is discarded.

[0093] The operation of a cooling system for the internal combustionengine 1, including the Rankine cycle system 2, will be described belowmainly with reference to FIGS. 1 and 2.

[0094] The water pumped from the tank 6 by the lower-pressure pump 7 issupplied via the passage P1 to the heat exchanger 102 mounted in theexhaust pipe 101, where it is preheated. Then, the water is supplied viathe passage P2 to the water jacket 105 of the internal combustion engine1. The water flowing within the water jacket 105 cools the cylinderblock 103 and the cylinder head 104 which are the heated portions of theinternal combustion engine 1, and this water is supplied in atemperature-raised state to the dispensing valve 106. The waterpreheated in the heat exchanger 102 in the exhaust pipe 101 is suppliedto the water jacket 105, as described above, and hence, when thetemperature of the internal combustion engine 1 is lower, the warming ofthe engine 1 can be promoted. In addition, performance of the evaporator3 can be enhanced by preventing the overcooling of the internalcombustion engine 1 to raise the temperature of the exhaust gas.

[0095] A portion of the higher-temperature water dispensed by thedispensing valve 106 is pressurized by the higher-pressure pump 8 andsupplied to the evaporator 3, where it is subjected to the heat exchangewith the exhaust gas and thus converted into a higher-temperature andhigher-pressure vapor. The higher-temperature and higher-pressure vaporgenerated in the evaporator 3 is supplied to the vapor supply pipe 75for the expander 4; passed through the cylinders 33 and the vanechambers 50 to drive the rotary shaft 21 and then discharged from thedischarge bore 17 b.

[0096] Another portion of the higher-temperature water dispensed by thedispensing valve 106 is depressurized by the reducing valve 107incorporated in the passage P5 and thus converted into a vapor, which issupplied to the relay chamber 19 in the expander 4. The vapor suppliedto the relay chamber 19 is joined with the first dropped-temperature anddropped-pressure vapor supplied from the vapor supply pipe 75 and passedthrough the cylinders 33, and the resulting mixture drives the rotaryshaft 21 and is then discharged from the discharge bore 17 b. Asdescribed above, a portion of the higher-temperature water from thedispensing valve 106 is vaporized by the reducing valve 107 and suppliedto the expander 4 and hence, the heat energy received in the waterjacket 105 of the internal combustion engine 1 by the water can beutilized effectively to increase the output from the expander 4. Inaddition, the other portion of the higher-temperature water dispensed bythe dispensing valve 106 is supplied via the passage P6 to the firstwater passage W1 in the expander 4 to lubricate various portions to belubricated. Because the portions to be lubricated of the expander 4 arelubricated using the higher-temperature water, as described above, theexpander 4 can be prevented from being overcooled, thereby reducing thecooling loss. The water entering the vane chambers 50 in the expansionstroke after the lubrication is mixed with the vapor existing in thevane chamber 50, whereby it is heated and vaporized to increase theoutput from the expander 4 by the action of its expansion. The seconddropped-temperature and dropped-pressure vapor discharged from thedischarge bore 17 b in the expander 4 to the passage P8is supplied tothe condenser 5, where it is cooled by the cooling fan 19 to becomewater and returned to the tank 6. The other portion of thehigher-temperature water dispensed by the dispensing valve 106 is cooledby the heat exchange with the auxiliary 110 incorporated in the passageP7 and then returned via the check valve 111 to the tank 6.

[0097] As described above, the following water-circulating paths arecombined with each other: a water-circulating path through which thewater pumped from the tank 6 by the lower-pressure pump 7 is supplied tothe water jacket 105 to cool the heat d portions of the internalcombustion engine and thereafter, the water is supplied the water to theauxiliary 110 to cool it and then returned to the tank 6; and awater-circulating path in the Rankine cycle system 2, through which aportion of the water exiting from the water jacket 105 is dispensed asthe working medium and returned via the higher-pressure pump 8, theevaporator 3, the expander 4 and the condenser 5 to the tank 6. Thewater-circulating path in the cooling system for the internal combustionengine 1 is of a lower-pressure and a larger flow rate, and thewater-circulating path in the Rankine cycle system 2 is of ahigher-pressure and a smaller flow rate. Therefore, the water having aflow rate and a pressure suitable for each of the cooling system for theinternal combustion engine 1 and the Rankine cycle system 2 can besupplied, the heated portions of the internal combustion engine 1 can becooled sufficiently to disuse a radiator, while maintaining theperformance of the Rankine cycle system 2. Moreover, the water suppliedfrom the lower-pressure pump 7 to the water jacket 105 is preheated bythe heat exchanger 102 mounted in the exhaust pipe 101 and hence, thewaste heat from the internal combustion engine 1 can be utilized furthereffectively.

[0098] In addition, the heat exchanger 102 for receiving thelower-temperature water supplied from the lower-pressure pump 7 ismounted at the location downstream of the exhaust pipe 101 where thetemperature of the exhaust gas is lower than that at the location of theevaporator 3 and hence, the surplus waste heat possessed by the exhaustgas can be recovered effectively and thoroughly. Further, because thewater preheated by the heat exchanger 102 is supplied to the waterjacket 105, the overcooling of the internal combustion engine 1 can beprevented, and the temperature of the combustion heat, namely, theexhaust gas can be raised, whereby the heat energy of the exhaust gascan be increased, leading to an enhancement in waste heat recoveryefficiency.

[0099] Although the embodiment of the present invention has beendescribed in detail, it will be understood that various modifications indesign may be made without departing from the subject matter of thepresent invention.

[0100] For example, the water (vapor) is illustrated as the workingmedium in the embodiment, but according to the present invention, anyother working medium such as ammonia and the like can be employed.However, the water is suitable as a lubricating medium also serving as aworking medium, because of a wider range of temperature in which thewater can be used without variation in composition such ascarbonization, and the higher-temperature vapor as the working mediumsupplied to the expander 4 and the water as the relativelylow-temperature lubricating medium discharged from the water jacket 105of the internal combustion engine 1 can be mixed with each other withouthindrance.

INDUSTRIAL APPLICABILITY

[0101] The Rankine cycle system for the internal combustion engineaccording to the present invention is suitable for an automobile, butcan be applied to any internal combustion engine other than theautomobile.

What is claimed is:
 1. A Rankine cycle system for an internal combustion engine, including an evaporator (3) for heating a liquid-phase working medium by a waste heat from an internal combustion engine (1) to generate a gas-phase working medium, an expander (4) for converting a heat energy of the gas-phase working medium discharged from said evaporator (3) into a mechanical energy, a condenser (5) for cooling the gas-phase working medium discharged from said expander (4) to restore the gas-phase working medium into the liquid-phase working medium, a tank (6) for storage of the liquid-phase working medium discharged from said condenser (5), and pumps (7, 8) for supplying the liquid-phase working medium in said tank (6) to said evaporator (3), characterized in that said pumps (7, 8) are a lower-pressure pump (7) and a higher-pressure pump (8), said lower-pressure pump (7) having the liquid-phase working medium in said tank (6) pass through a cooling means (105) for the internal combustion engine (1), thereby heating and supplying the liquid-phase working medium to a dispensing valve (106), a portion of the liquid-phase working medium dispensed by said dispensing valve (106) being pressurized by said higher-pressure pump (8) and supplied to said evaporator (3), another portion of the liquid-phase working medium dispensed by said dispensing valve (106) being discharged to said tank (6) after dissipating its heat in an auxiliary (110).
 2. A Rankine cycle system for an internal combustion engine according to claim 1, wherein the liquid-phase working medium exiting from said lower-pressure pump (7) is preheated in a heat exchanger (102) mounted in an exhaust pipe (101) in the internal combustion engine (1) and supplied to said cooling means (105).
 3. A Rankine cycle system for an internal combustion engine according to claim 1 or 2, wherein a portion of the heated liquid-phase working medium dispensed from said dispensing valve (106) is used as a lubricating medium for said expander (4).
 4. A Rankine cycle system for an internal combustion engine according to claim 3, wherein the portion of the liquid-phase working medium supplied as the lubricating medium is supplied to an expansion stroke of said expander (4).
 5. A Rankine cycle system for an internal combustion engine according to claim 2, wherein a portion of the heated liquid-phase working medium dispensed from said dispensing valve (106) is passed through a reducing valve (107) to be converted into a gas-phase working medium, which is supplied to an expansion stroke of the expander (4).
 6. A Rankine cycle system for an internal combustion engine according to any one of claims 1 to 5, wherein water is used as the liquid-phase working medium. 